That was last week. As with all things Obama, the storyline reported by the mainstream media obfuscates the truth. Now, via the Army Times, we learn that the 50,000 U.S. troops remaining in Iraq include seven "Advise and Assist Brigades," two air combat brigades and two National Guard infantry brigades. The "Advise and Assist Brigades" are distinguished from "full" combat brigades by additional training prior to deployment:

The Army has three different standard brigade combat teams:
infantry, Stryker and heavy. To build an Advise and Assist Brigade, the
Army selects one of these three and puts it through special training
before deploying.

The smoke and mirrors re-designation allows the "advisory" brigades to retain an inherent capability to conduct offensive and defensive operations. These brigades can shift
operational focus from security force assistance to combat operations as required.

In other words, Obama just gives combat brigades still deployed in Iraq a new designation and declares the combat mission over.